The invention relates to a method for manufacturing filled containers, wherein a preform of a thermoplastic material, after a thermal conditioning along a transport path, is deformed in the area of a heating section within a mold by applying pressure in the container, and wherein a filling medium to be filled into the container is used as the fluid for container deformation.
The invention further relates to a device for manufacturing filled containers of a thermoplastic material which includes at least one heating section arranged along a transport path of a preform, and a molding station provided with a mold, and wherein the molding station includes a feeding device for a filling medium to be filled into the container.
When a container is formed by the influence of blowing pressure, the preforms of a thermoplastic material, for example, preforms of PET (polyethylene terephthalate), are supplied within a blow molding machine to different processing stations. Typically, such a blow molding machine includes a heating device and a blow molding device in whose area the previously thermally conditioned preform is expanded into a container by biaxial orientation. The expansion takes place by means of compressed air which is admitted into the preform to be expanded. The process-technical sequence in such an expansion of the preform is explained in DE-OS 43 40 291. The introduction of the pressurized gas mentioned in the beginning also includes the introduction of compressed gas into the developing container bubble, as well as the pressurized gas introduction into the preform at the beginning of the blow molding process.
The basic construction of a blow molding station for molding containers is described in DE-OS 42 12 583. Possibilities for thermally conditioning the preforms are explained in DE-OS 23 52 926.
In accordance with a typical processing method, the blow molded containers manufactured as described above are fed to a subsequent filling device and are there filled with the intended product. Consequently, as a rule, a separate blow molding machine and a separate filling machine are used. It is also already known to couple a separate blow molding machine and a separate filling machine directly to each other and to thereby make available a so-called blocked blowing/filling device.
Moreover, it is also already known to carry out molding of the container by means of the filling material itself to be filled. For this purpose, an appropriately thermally conditioned preform is placed into a suitable mold and subsequently the liquid filling medium is conducted into the preform and the container bubble which develops in this preform. In this process, the container bubble is expanded until a complete contact at the inner contour of the mold is achieved and the container is filled. Such a method is also called a hydraulic molding method.
In a molding of the container by the filling medium itself, only one machine is still needed which however, has an increased complexity. However, first test results with such devices show that the quality of the manufactured containers is still significantly below the quality of conventionally manufactured blow molded containers. This is essentially due to the fact that a plurality of process parameters are available when carrying out a blow molding process which are not present or could not yet be determined in a hydraulic molding of containers.